Here are pictures of the lock. Inside it is stamped 065 1/2, the lock assembly number must be 71 as all parts are stamped with it, there is another number following two Y's laid on the side then 24200.We'll start with the empty case. Note the spring on the left side (top of case) it is for the lever operated by the time lock which blocks the friction fence. (shown later)
The dial spindle is mounted inside the door and stays there unless the door is dissembled. With the lock case mounted, the spindle drive gear and the drive wheel must be timed and held in place while one reaches around the door to thread the spindle into the gear. On this lock the dial not only operates the lock and extends the lock bolt, it also moves all the linkage in the door and the four door bolts. This puts some extra pressure on the gears and fence. After the locks are removed and the 1/2" thick plate beneath them, one can see the door bolt linkage. The dial has to push the door bolt with the pin which pivots the dog leg which rotates the 1/2" thick round steel plate which pivots the other three dog legs which push out the remaining three door bolts. Whew, a lot of mass.
Under the linkage is a threaded bung that holds the spindle in. Once the spindle is out you can see it is a substantial piece with a large flange to prevent punching and a taper fit to the door to prevent introduction of liquid explosives.
Back to the lock. Here, the spindle drive gear, the drive wheel, and the gear for the friction fence are in place.
On other Yales I have seen, the friction fence is an assembly consisting of the drive gear with shaft that is put through the fence and then crimped into place. Between the fence and the shaft is a spring wound around the shaft to create the needed friction to turn the fence into the gates of the wheel pack. In this lock the fence just slides over the shaft. But something is not right as enough friction is not created to consistently engage the fence. Inside the fence there are two grooves each .010 deep. I assume there should be some sort of inserts in them? This is the inside of the fence.
With the fence and wheel pack in place the lock is complete. Note that the case cover has a lock tab to keep the wheel pack assembly in place and has supports for the fence bolt and the shaft that the time lock lever pivots on. A spring was added to the fence to make up for what ever is missing inside of it. Who ever adapted the spring to this application did a nice job and it does what it needs to do.
On most cannonball type safes the combination lock is just a day lock that makes turning the door with the crank impossible, all done on the front side of the door. The true security, the inner door bolts, are operated by the time lock. National's choice to have the dial operate everything puts quite a load on the lock internals, and the parts show it. The door linkage can keep pressure on the fence causing it to drag heavily on the drive wheel which is larger then the rest of the wheels in the wheel pack. Here is the wear pattern on the drive wheel. Very rough. The fence does't make contact with the full width of the drive wheel, hence, the uneven wear to one side.
The fence is worn where it rides on the drive wheel. Also the tip of the fence and the contact edge of the drive wheel gate are rounded off from the initial contact of starting all that door linkage moving before the rest of the wheel pack gates assist it. Here you can see how the fence is kept off of the wheel pack by the slightly larger diameter of the drive wheel.
So as you can see there needs to be some tweaking done to improve the performance of this lock. A shim washer under the drive wheel to align it better with the fence helps. The leading edge of the fence will need to be trued up. I am considering opening up the gates on the wheels a bit to make the dialing more forgiving and to help the fence to drop in deeper. Narrowing the fence slightly would do the same thing. I will need to add a stopper to the door linkage so it doesn't get thrown to far as it will then prevent the fence from turning in at all. I am open to any suggestions.
I don't see how this lock could be manipulated in this condition. Between the rough dialing from the bumpy drive wheel and the excessive drag from the door linkage causing the fence to drag on it, it is challenge just to dial the known combination.
On a different note: This was dropped off today. A 1907 National cash register. Its gonna look great setting on one of the safes, especially this National manganese money chest.
Next time, if I can find the courage, maybe I will tell about the lock out I experienced.
It is time... stand up for a constitutional America. Without it, we have shed blood in vain.